I am trying to create a dropdown list that when I select an item from the list it adds the item into a text box but doesn't delete the previous text box item. I am just struggling with how to get the text field to concatenate and not simply replace the existing data with the new. I thought it might be something I could do with action builder but it doesn't seem possible with out additional scripting.
Try this code on the exit event of your dropdown list:
tfList.rawValue = tfList.rawValue + " " + this.rawValue;
I'm presuming that the list you're adding items to is called tflist. If it doesn't work, let us know.